1. Field of the Invention
The present invention relates to an information processing apparatus for connecting an external device in conformity with a predetermined interface specification, and particularly relates to an information processing apparatus for connecting an external device in conformity with HDMI (High Definition Multimedia Interface).
More specifically, the present invention relates to an information processing apparatus which operates as an HDMI source, detects the validity of connection to an external device serving as an HDMI sink, and in the event of valid connection, acquires device information to output a suitable video signal, and particularly relates to an information processing apparatus for controlling a power saving operation according to the validity of connection to an HDMI sink.
2. Description of the Related Art
The HDMI (High Definition Multimedia Interface) is an interface standard principally designed for digital video and audio input/output for a household appliance or AV equipment (e.g., see High-Definition Multimedia Interface Standard Version 1.3), and specifically, an arrangement is made wherein the DVI (Digital Visual Interface) which is a digital interface employed for connection between a personal computer and a display is further advanced so as to send/receive video signals, audio signals, and bidirectional control signals with a single cable, thereby simplifying cable connections. Also, with an optional arrangement, a control signal can be transmitted in bidirectionally, and multiple AV devices can be controlled with a single remote control by relaying between the devices.
With HDMI, TMDS (Transition Minimized Differential Signaling) which is a digital transmission system for a display video signal also employed for the DVI is applied to a physical layer, whereby high speed digital data transmission can be realized. TMDS is a technique for differentially transmitting digital data, and is configured of a link made up of four channels in total each of which is assigned to the transmission of each of three types of video signals of R (Red), G (Green), and B (Blue), and a reference clock signal, respectively. Each of the video signals transmits 10-bit data per one clock cycle by serially converting a 10-bit parallel signal. For example, in the event of employing a 500-MHz clock, video data of 5G bits per one second can be transmitted (the effective transmission rate of the HDMI version 1.3 is 250 Mbps through 3.4 Gbps).
For example, a video signal processing apparatus has been proposed, which includes a specification information acquiring unit for acquiring specification information indicating the specification of a monitor connected to a digital video output terminal, a selection operation accepting unit for accepting the selection operation of a user who selects the type of the analog video output terminal of the monitor connected to an analog video output terminal, a setting operation accepting unit for accepting the setting operation of a user who prioritizes one of the specification information acquired by the specification information acquiring unit and the selection operation of a user accepted by the selection operation accepting unit, and a determining unit for determining the resolution of the video signal to be output based on the specification information acquired by the specification information acquiring unit, and the selection operation of a user accepted by the selection operation accepting unit, and the setting operation of a user accepted by the setting operation accepting unit (see Japanese Unexamined Patent Application Publication No. 2006-319502).
FIG. 8 schematically illustrates the configuration of an HDMI communication system in which an HDMI source is connected to an HDMI sink over HDMI cables. Also, FIG. 9 illustrates the pin array of an HDMI interface connector (type A in this case) (see Table 1). An HDMI source for supplying a video signal, and an HDMI sink for playing and outputting a video signal are mutually connected via an HDMI interface. The HDMI source reads out resolution information called as EDID (Extended Display Identification Data) from EDID ROM within the HDMI sink, and converts this into resolution compatible with the sink side, and outputs the converted video signal.
TABLE 1PINPINNUMBERSIGNALNUMBERSIGNAL1TMDS DATA 2+2TMDS DATA 2SHIELD3TMDS DATA 2−4TMDS DATA 1+5TMDS DATA 16TMDS DATA 1−SHIELD7TMDS DATA 0+8TMDS DATA 0SHIELD9TMDS DATA 0−10TMDS CLOCK+11TMDS CLOCK12TMDS CLOCK−SHIELD13CEC14RESERVED (N.C. ONDEVICE)15SCL16SDA17DDC/CEC GROUND18+5 V POWER19HOT PLUG DETECT
For example, a camcorder including an HDMI interface serving as an HDMI source supplies the video of a captured moving image or still image to an HDMI-capable television monitor, whereby the video can be output on the screen thereof.